Here are the steps:
1) Log in to the WintellectNOW site.
2) Click your name in the upper-right corner of the page, and then select "My Profile."
3) Click the account that you wish to disable auto-renewal for under "You are an administrator for the following accounts."
4) Click the "Cancel" button under "Subscription Information."
5) Click the "Cancel Subscription" button in the ensuing dialog.
You will continue to enjoy access to WintellectNOW until your subscription expires, but the subscription will not auto-renew.